This invention relates to a flame-retardant flexible polyurethane foam.
Flexible polyurethane foams are widely employed in such products as mattresses and seating where safety considerations require that they exhibit effective fire retardant properties. The typical flexible polyurethane foams of commerce do not inherently possess satisfactory resistance to ignition and/or flame propagation but can be made to do so by the addition of one or more flame retardant substances thereto, generally to the foam-forming compositions or to a component thereof before, or as, the foam-foaming reaction takes place.
Halogenous as well as non-halogenous phosphorus-based compounds are known for use as fire retardants in flexible polyurethane foams. Illustrative of such compounds and flexible polyurethane foams incorporating them in flame retardant-effective amounts are those disclosed in U.S. Pat. No. 4,623,672 (1-phosphonoethane-2-carboxylic acid-tri-C1-C4 alkyl esters); U.S. Pat. No. 4,656,200 (amine salts of phosphonic acids); U.S. Pat. No. 4,666,967 (salt formed by reaction between dimethyl methyl phosphonate, monomethyl methyl phosphonate or methyl phosphonic acid and an organonitrogen compound such as urea, dicyandiamide, guanidine, aminoguanidine, thiourea, N-methyl urea, N-allyl urea, N,N′-diallyl urea, N,N′-dimethyl urea, ethylene urea, biurea, (thio) acetamide, (thio) propionamide, (thio) butyramide, (thio) octanamide, malonamide, mono- or di-thio malonamide, succinamide, mono- or di-thio succinamide, sebacamide, pyrrolidone, piperidinone, (thio) caprolactam and (thio) dodecalactam); U.S. Pat. No. 5,276,066 (1,3,2-dioxaphosphorinan)amines); U.S. Pat. No. 6,262,135 (blend of monomeric halogenated organic flame retardant, e.g., a halogenated phosphate ester such as tris(dichloropropyl)phosphate, tris(2-chloroethyl)phosphate, tris(dibromopropyl) phosphate, tris(bromo-chloropropyl)phosphate, and the like, and an oligomeric organophosphate, e.g., the reaction product of a polyphosphate ester (obtained by the reaction of phosphorus pentoxide and a trialkyl phosphate such as triethylphosphate) with an epoxide such as ethylene oxide); U.S. Pat. No. 6,380,273 (hydroxyalkylphosphonates); and, U.S. Pat. No. 6,861,452 (a halogen-free phosphate ester that possesses at least one alcoholic hydroxyl group, has an acid value of 2 mg KOH/g or less, a viscosity f 5 Pa·S or less at 25° C., a hydroxyl value of 5 to 250 KOH mg/g, and a weight average molecular weight of 200 to 2000); DE 3803030 (phosphonate obtained by the transesterification of dimethyl methyl phosphonate with a diol or diphenol in the presence of sodium methylate); DE 19853025 (mixture of dimethyl-1-hydroxyethane phosphonate and diethyl ethyl phosphonate or diphenylcresyl phosphate); EPA 0 245 207 (salts of dimethyl methyl phosphonate); EPA 0 908 464 (dimethyl-1-hydroxymethane phosphonate); and, UK Patent Application GB 2 319 251 (halogen-free, oligomeric or polymeric, alkylene-bridged alkyl phosphonates).